Greece: Crete-Attica electricity interconnection enters final testing phase

Greece’s electricity transmission system operator, ADMIE, along with its project implementation arm Ariadne Interconnection, has reached a key milestone in the Crete-Attica electricity interconnection project. A final inspection at the Damasta converter station in Heraklion marks the beginning of the last phase of testing, ahead of the launch of the trial operation. The facility is expected to be energized next week, introducing reactive power into Crete’s electricity grid.

In parallel, trial electrification of the 400 kV cable system in Attica is underway. This segment connects the Koumoundouros converter station to the national grid, with full system testing scheduled to begin later in May.

By the end of the month, active electricity transmission from Attica to Crete is expected to begin. The Crete-Attica interconnection is Greece’s most ambitious and technically complex electricity transmission project to date.

Since early 2025, extensive testing has been carried out on all equipment. The 150 kV Damasta substation has been fully integrated into Crete’s network, and the 500 kV underground and subsea cables linking the two converter stations have passed all required tests. A significant step forward also came with the recent approval of the environmental permit for the new 150 kV Chania–Damasta transmission line in western Crete. This line will play a critical role in enabling the island’s dual interconnections—with both Attica and the Peloponnese—to operate smoothly and simultaneously.